Catalytic hydroprocessing refers to petroleum refining processes in which a carbonaceous feedstock is brought into contact with hydrogen and a catalyst, at a higher temperature and pressure, for the purpose of removing undesirable impurities and/or converting the feedstock to an improved product. Examples of hydroprocessing processes include hydrotreating, hydrodemetalization, hydrocracking and hydroisomerization processes.
A hydroprocessing catalyst typically consists of one or more metals deposited on a support or carrier consisting of an amorphous oxide and/or a crystalline microporous material (e.g. a zeolite). The selection of the support and metals depend upon the particular hydroprocessing process for which the catalyst is employed.
Petroleum refiners continue to seek out catalysts of improved activity, selectivity and/or stability. Increasing the activity of a catalyst increases the rate at which a chemical reaction proceeds under a given set of conditions, increasing the selectivity of the catalysts decreases unwanted by-products of the reaction, and increasing the stability of a catalyst increases its resistance to deactivation, that is, the useful life of the catalyst is extended. In general, as the activity of the catalyst is increased, the conditions required to produce a given end product, such as a hydrocarbon of a particular sulfur or nitrogen content, becomes more mild (e.g. decreased temperature). Milder conditions require less energy to achieve a desired product, and the catalyst's life is extended due to such factors as lower coke formation and the like.
It is well known in the art that modest or slight variations in compositional characteristics or methods of preparing hydroprocessing catalysts have been known to have highly unpredictable activity, selectivity and/or stability effects on hydroprocessing reactions (such as denitrogenation and/or desulfurization reactions). Accordingly, because of this unpredictability in the art, there continues to be new and surprising improvements in activity, selectivity and/or stability of hydroprocessing catalysts.